The invention generally relates to fluid processing systems and methods. More particularly, the invention relates to blood processing systems and methods.
Certain on-line blood collection procedures entail the processing of relatively large volumes of whole blood. This, in turn, requires the introduction of relatively large volumes of anticoagulant to the whole blood during processing period. It is important to accurately monitor the total volume of anticoagulant used during the procedure. This task becomes complicated when the operator is called upon to periodically pause the procedure to replenish the anticoagulant supply.
The invention provides systems and methods for keeping accurate track of a total fluid volume administered from a fluid source that can be periodically replenished during a fluid processing procedure.
One aspect of the invention provides fluid processing systems and methods that make use of a replenishable source containing a volume of a processing fluid. The systems and methods include a circuit to dispense the processing fluid from the source during a processing period. A weigh sensor is coupled to the source and operates to sense weight of the source. Knowing the density of the processing fluid, the weight translates to volume of processing fluid present in the source.
The systems and methods further include a processor coupled to the weigh sensor. The processor operates in response to commands to sequentially pause and resume the processing period. The processor includes a counting function that operates in a series of processing steps. The processing steps (i) record a current weight value of the source at commencement of the processing period; (ii) register a first subsequent weight value (Wt1) of the source upon pause in the processing period; (iii) register a second subsequent weight value (Wt2) of the source upon resumption of the processing period following the pause; (iv) generate an updated current weight value upon resumption of the processing period by adding to the current weight value the difference between Wt2 and Wt1; (v) register a final weight value of the source at termination of the processing period; and (vi) generate a total volume value of processing fluid dispensed from the source during the processing period, by subtracting the final weight value from the updated weight value. Due to the processing steps followed, the total volume value will take into account replenishment of the processing fluid when the processing period is paused.
Another aspect of the invention integrates the fluid processing systems and methods just described into blood processing systems and methods. According to this aspect of the invention, the processing fluid is introduced into a blood processing circuit. In one embodiment, the blood processing circuit separates blood into component parts. In this embodiment, the processing fluid comprises an anticoagulant solution that is added to the blood during processing.